[unreadable] [unreadable] This proposal focuses on a novel system for the electrochemical detection of cancer related protein targets using a nanoscale electrode platform. The assay proposed relies on an electro catalytic process involving two transition-metal ions that reports on biomolecular complexation events. Because the reporter system responds to changes in the electrostatics of an electrode surface, it will enable the analysis of nucleic acids/protein and peptide/protein complexes. The proposed project has 3 specific aims: 1) electro catalytic detection of DNA repair proteins implicated in cancer using DNA-modified electrodes; 2) optimization of electro catalytic detection and multiplexed analysis of cellular DNA repair activities, and 3) development of a generalized electro catalytic protein detection method using prostate cancer biomarkers. The electro catalytic protein detection system described is advantageous because it will allow the analysis and discrimination of multiprotein complexes in addition to uncomplexed analytes and will have high selectivity and specificity. Additionally, the protein detection assays will be conducted using nanoelectrodes that will allow multiplexed detection of panels of different biomolecular targets. [unreadable] [unreadable]